Electric circuit breaker



Jan. 12, 1960 E- B- JUDD ET AL ELECTRIC CIRCUIT BREAKER Filed Aug. 22,1957 5 Sheets-Sheet 1 INVENTORS' EDWIN Bduoo, JOHN D. Youme ATTORNEYJan. 12, 1960 E. B. JUDD ETAL 2,921,169

ELECTRIC CIRCUIT BREAKER Filed Aug. 22, 1957 3 Sheets-Sheet 2 INVENTORSEDWIN B. d UB0,

1: 1111/1/11 VII/l JOHN D. YOUNG Jan. 12, 1960 E. B. JUDD ET AL2,921,169

ELECTRIC CIRCUIT BREAKER Filed Aug. 22, 1957 3 Sheets-Sheet 3 INVENTORSEnwm B. duoo, \JOHN D. Youme KM/ t C 7 United States Patent 2,921,169ELECTRIC CIRCUIT BREAKER Edwin B. Judd, Gonic, N.H., and John D. Young,Schenectady, N.Y., assignors to General Electric Company, a corporationof New York Application August 22, 1957, Serial No. 679,607

4 Claims. (Cl. 200153) Our invention relates to electric circuitbreakers and particularly to manually. operable circuit breakers adaptedto' control relatively high values of current.

A type of operating mechanism which has been generally satisfactory foruse in circuit breakers of low and medium ampere rating, such as 20-100amperes at 250 volts, is shown in Patent No. 2,640,127, assigned to thesame assignee as the present invention. This mechanism includes a togglelinkage supported on a releasable toggle carrier and applyingcontact-closing force through a straightening action of the togglelinkage. Difiiculties are encountered, however, when it is endeavored toadapt a mechanism of this type for use in circuit breakers of relativelyhigh rating, such as 800 amperes at 600 volts, where it is necessary tooperate large contacts at high speeds and to exert high contactpressures, all while maintaining a compact structure. It is found, forinstance, that an optimum arrangement of pivots for the mechanism forthe purpose of providing high contact force does not permit adequateopening movement of the contacts, and vice versa. In addition, the sizeand weight of the contacts makes high-speed automatic opening difficultto achieve.

It is anobject of our invention to provide a circuit breaker operatingmechanism of the type having a toggle linkage supported on a releasabletoggle carrier which is adapted to occupy a relatively small space andto exert maximum contact force while also providing a maximum amount ofcontact opening movement.

Another objectof our invention is to provide a circuit breaker forrelatively high currents and voltages including a composite contactmember comprising articulated main or current-carrying contacts andarcing or current-interrupting contacts so arranged that the speed ofopening helps to provide a predetermined desired sequence of openingthereof.

In accordance with our invention, we provide an electric circuit breakerhaving an operating mechanism including a collapsible toggle linkageadapted to hold a pair of contacts closed when in straightenedcondition. The toggle linkage is movable as a whole to a trippedposition. An auxiliary lever is provided which is adapted to engage thetoggle linkage to partially collapse it while it is moving towardtripped condition. This action provides an amount of contact openinggreater than would otherwise be possible. It also provides anaccelerated contact opening action, which, combined with speciallydesigned movable contact assemblies, affords a selective contact openingaction. The selective action causes the main or current-carryingcontacts to open first, and the ,arcing or current interrupting contactsto open last.

In accordance with this latter aspect of our invention, we furtherprovide a contact assembly including at least one main orcurrent-carrying contact, and one arcing or current-interruptingcontact. Each contact is pivotally supported on a contact arm. Theweight of each contact is so distributed with respect to its pivotalsupport that f ice iii a high-speed automatic opening operation, inertiacauses the main contacts to open first, and the arcing contacts to opensecond, thereby providing a more effee= tive and less-damaginginterrupting action.

Additional aspects of our invention will be pointed out in the followingdetailed description and illustrated in the accompanying drawings, whilethe scope of our invention will be more particularly pointed out in theappended claims.

In the drawings,

Figure 1 is a side elevation view partly in section, of an electriccircuit breaker incorporating our invention;

Figure 2 is a side elevation view of the operating mechanism of thecircuit breaker of Figure 1, the near side of the mechanism supportingframe being removed forclarity, and the parts being shown in the oncondi. tion;

Figure 3 is a view similar to Figure 2, the parts being;

shown in the tripped condition;

Figure 4 is an exploded view in perspectiveof'some; of the parts of themechanism of Figures; 1 and 2;

Figure 5 is an elevation viewofja modified form- Off the invention ofFigure 1; and.

Figure 6 is an exploded view. invperspective of some of the parts of themechanisrnof Figure 5.

In the drawings, we haveshownour invention as em-. bodied in athree-poleelectric circuit breakercomprising; an insulating outer ormain insulating casing having in base 10 and a cover 11.

Monnted on the base 10: at oneend; thereof are; threeload ter minals, 12(only one shown) and, at the; opposite end of-the base 10 three lineterminals 13 (only one shown). The line terminals 13; are each connectedto line contact straps 14 carrying at the opposite end thereof a pair ofside-by-side stationary main contacts 15 (only one shown.) and astationary arcing contact 16, the three contacts being arranged in atriangular configuration.

Each of the main and arcing contacts 15 and 16 of each pole cooperateswith a corresponding movable main contact 17 and a movable arcingcontact 18, respectively.

26, carried by the base 10.

The movable arcing contact member 18 of each poles has most of itsweight forward of the pivot pin 19'.' Each of the movable main contactshas most of its weight; to the rear of the pivot pin 19'. The effect ofthis is that:-

the inertia of the contacts causes the main contacts tm open first andthe arcing contact to open last, which is: the desired sequence. Themovable contacts 17 and of each pole are connected by means ofmulti-strand fleflb ible braids 21 to one terminal 22 of the trip unit23, and the load terminal 24 of the trip unit 23 is connected directlyto the main load terminal 12 of the circuit breaker.

For the purpose of moving the movable contacts 17 and 18 into and out ofengagement with the stationary or line contacts 15 and 16, both manuallyand automatically, we provide a main operating mechanism indicatedgenerally at 25. The operating mechanism 25- includes a generallyU-shaped supporting frame member- 26 and a plurality of parts pivotallysupported between the opposite sides thereof. These parts includethree-v contact arms 19, there being one contact arm for each pole ofthe circuit breaker.

The contact arms 19 are adapted to be rotated about,

their pivotal support by means of a toggle action linkage j includingthe toggle links 27 and 28 connected together:

.straightenedand collapsed positions by means ofan p 7 erating handle 32in cooperation with a pair 'o'f 'tension typesprings 33 interconnectedbetween the-handle 32 and the knee point 29 of the toggle linkage 27,28.

When the handle member 32 is in the position shown in' Figure 1, thecontacts are in closed position, and when the handle is movedcounterclockwise from this position toward-.the left end of the breakeras viewed, the contacts aremoved to the open' circuit position.

The end 31 of the toggle carrier 31 is formed to act as a latchingelement and to engage an intermediate latch member 34 which is pivotallysupported on a pin 35 carried by an extension 26 of the frame 26. Theaction of the tension springs 33 is such as to bias the togglef carrier31 for rotation in a clockwise direction. The toggle carrier 31 isrestrained from movement in such a direction, however, by its engagementwith-the intermediate latch member 34. A biasing spring, 34, constantlyurges the intermediate latch 34in a clockwise direction as viewed in thefigures. By reason of the greaterforce exerted on it by the togglecarrier 31, however, the intermediate latch member 34 is biased in acounterclockwise direction whenever the breaker is latched. I i

For the purpose of normally restraining the intermediate latch member,and therefore the toggle carrier 31 and the operating mechanism as awhole, in the on position except in the case of predetermined overloadconditions, we provide a trip unit generally indicated at 23. Theparticular construction and operation of the trip unit .is not criticalto our present invention and any suitable type may be used. Theparticular trip unit illustrated, however, is described more fully andclaimed in an application filed concurrently herewith by H. M.

Steven and R- W. Marshall, and assigned to the same assignee as thepresent invention.

The trip unit 23.includes a latch member '36 adapted normally to preventthe intermediate latch member 34 from rotating in a counterclockwisedirection. The latch member 36 ,is pivotally supported on the trip unit23 on a pivotpin 37,extending through aligned openings in a boss 38molded integral with the housing of the trip unit 23. t

Thelatch member 36 carries a latch roller 39 supported on a pin 40extending between opposed, spaced apart, portions of the latch member36. The intermediate latch member 34 is provided with a cam surface 41which, when the breaker is latched, as shown in Figure 1, bears againstthe roller 39 and biases'the latch member 36 in' a counterclockwisedirection, that is, to the left as-viewed in the figures. The latchmember 36 is prevented from moving to the left by means which isreleasable upon the occurrence of predetermined current conditions. Whenreleased by such current-responsive means, the latch 36 moves to theleft, allowing the intermediate latch member 34 to rotatecounterclockwise, releasing-the carrier 31. Following such release, theintermediate latch 34 is moved clockwise by its bias spring 34 against astop portion of the frame 26.

In order to reset the breaker following a tripping operation; the handle'32 is moved manually to the left as viewed to and slightly beyond thenormal off position. During this movement, a portion 32' of the handleengages 'the carrier 31 and rotates it counterclockwise. When "the latchtip of the carrier 31 engages the surface 345 of the intermediate latch34, further counterclockwise movement of the carrier causes theintermediate latch 34 to move to the left, as viewed, with a combinedpivoting and sliding action, as permitted by the elongated pivot notch34N. The ends of the bias spring 34'also are adapted to slide along theinner surface of the portion 34S- to permit this sliding retractingaction. The,

latch tip 31' of the carrier 31 finally clears the latch surface of theintermediate latch 34, and the intermediate latch is returned to itsnormal position by the action of the spring 34, thereby relatching thebreaker.

When the toggle carrier 31 is released from the intermediate latch 34,the carrier 31 is rotated in a clockwise direction by the action of'themain operating springs to the position substantially as shown in Figure3. As the pivot point 29 moves upwardly, the contact arms 19 are alsomoved upwardly or in a counterclockwise direction, toward open circuitposition. Because of the necessary proportioning and dimensions andarrangement of the parts, it will be found that, for substantial angularopening movement and maximum contact pressure, it is not possible toallow the toggle carrier" to rotate clockwise far enough to carry thepivot pin 30 definitely across the center line of action of themainsprings 33.

The action of the parts, as so far described, therefore, is such as tomove themovable contact arm 19 in an opening direction by movementof thetoggle'linkage upwardly I as a whole, without any substantial breakingor collapsing thereof The distance through which the movable contact ismoved by this means; however, is not as great as is ordinarily desirablefor circuit breakers of the rating of the subject device, i.e., 600 to800 amperes at 600 volts.

In order to provide additional contact opening movement, and also toaccelerate the contact opening movement, we provide a toggle lever 43supported on a pivot pin 44 between the sides of the mechanism frame 26.j

The 'toggle lever 43 is movable independently of the toggle carrier 31,and is biased by a biasing spring 45 in a counterclockwise directionagainst a portion 46 of the mechanism fram'e'26. The forward end' 43' ofthe toggle lever 43 is rounded and is adapted to coact with a projectionor'detent 47 on the upper toggle link 27 in a manner to be described.

As'longas the toggle carrier is in its latched conditlon as shown inFigure 2, the toggle lever 43 is maintained in theposition' shown inFigure 2. Thus the toggle linkage is moved between collapsedandstraightened'conditions without alteringithe position of the togglelever 43. 'When thetoggle carrier 31 is released from the intermediatelatch member 34, and rotates clockwise, however, the projection 47engages the rounded end 43 0f the toggle lever 43 and the twopartsrema-in 1n engage ment as further rotation of the toggle carrier 31occurs.

This action maintains the intermediate part of the upper toggle link 27at a' predetermined distance from the pivot pin'44, and causes thetoggle linkage to assume a slightly broken or collapsed condition asillustrated in Q Figure 3." This shortens, the distance betweenrtheopposite ends of the toggle linkage andresults in accelerating themovement of the contact arm 19 and inmoving the arm 19 further'in' acontact opening direction than would otherwise be possible. This isespecially true, and also especially important, when the handle 32 ismanuallyretained in the on or closed circuit position.

In'Figures' Sand 6 we have illustrated another embodiment of ourinvention, in which the toggle linkage 27,

'28 is adapted to be maintained in a slightly broken In this orcollapsed condition when tripping occurs. form, the projection 47 on theupper link 27 is omitted.

Insteadjthe toggle lever 49 is provided and the toggle carrier 50 isprovided with a rounded abutment or cam follower surface 51 adapted toengage the underside of the toggle lever 49 and to rotate the togglelever in a clockwisedirection as tripping occurs. The end 49, of thetoggle lever, engages the link 27 and forces the toggle linkage to acollapsed condition in a manner similar to that described in connectionwith Figures 2 and 3.

In the form of Figure 5 the end 49 of the toggle abutment 51 exerted onthe toggle lever 49 causes the point of engagement of the toggle lever49 to move upwardly along the toggle link 27 toward the upper pivotpoint 30'. In this manner, the leverage action of the toggle lever 49 onthe toggle link 27 is greatest at the initial point of movement anddecreases as the tripping action progresses. This aifords an importantprying action which assists in breaking any welds which might occurbetween the stationary and movable contacts, while at the same timeafiording a maximum rate of acceleration and a maximum opening distanceof the movable contact. While the toggle lever 49 has been shown as of adifierent configuration from the toggle lever 43, it will be apparentthat these toggle levers are substantially interchangeable.

While we have shown only two embodiments of our invention, it will beapparent that many modifications thereof may readily be made by thoseskilled in the art and we, therefore, intend by the appended claims tocover all such modifications as fall within the true spirit and scope ofour invention.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

' 1. An electric circuit breaker comprising a support, a contact armsupported on said support, a toggle carrier pivotally mounted on saidsupport, a toggle linkage conmeeting said contact arm and said togglecarrier, said toggle carrier being movable between latched and trippedpositions to move said contact arm between closed and opened positionsrespectively, a lever supported on said support for engaging and holdingsaid toggle linkage in partially collapsed position when said togglecarrier is in said tripped position, and means for guiding the movementof said lever in accordance with the movement of said toggle linkageduring movement of said toggle car- I rier to said tripped position.

2. An electric circuit breaker comprising a support, a contact armpivotally mounted on said support, a toggle carrier pivotally mounted onsaid support, a toggle linkage connecting said contact arm and saidtoggle carrier,

said toggle carrier being movable between latched and tripped positionsto move said contact arm between closed and opened positionsrespectively, a projection on said toggle linkage, a lever supported onsaid support adapted to engage and hold said toggle linkage in apartially collapsed position when said toggle carrier is in said trippedposition, said lever being adapted to be engaged by said linkageprojection and to be guided thereby during movement of said togglecarrier from said latched to said tripped position.

3. An electric circuit breaker comprising a support, a contact armpivotally mounted on said support, a toggle carrier pivotally mounted onsaid support, the toggle linkage connecting said contact arm and saidtoggle carrier, said toggle carrier being movable between latched andtripped positions to move said contact arm between closed and openedpositionsrespectively, a lever supported on said support and adapted toengage and hold said toggle linkage in a partially collapsed positionwhen said toggle carrier is in said tripped position, said togglecarrier having a cam follower projection adapted to engage said lever toguide the movement of said lever when said toggle carrier moves fromsaid latched to said tripped positiom 4. An electric circuit breaker asset forth in claim 1, said circuit breaker including means carried bysaid toggle carrier for engaging said lever and applying a force theretoat a point closely adjacent the pivot of said lever, the point ofapplication of said force being closely adjacent the pivot of said leverinitially and being more remote from the pivot of said lever as saidtoggle carrier moves to said tripped position.

References Cited in the file of this patent UNITED STATES PATENTS2,208,387 Pierce July 16, 1940 2,550,623 Teruzzi Apr. 24, 1951 2,581,181Favre Jan. 1, 1952 2,727,113 Mohr et a1. Dec. 13, 1955

